The invention discloses a system and a method for testing a temperature field of a shield main bearing. The system comprises a to-be-tested main bearing, a main bearing fixing seat, a loading system,a driving system, a base, a loading disk, a lubrication system and a control cabinet, wherein the to-be-tested main bearing is rotationally installed in a main bearing mounting cavity of the main bearing fixing seat; and the driving system, the loading system and the lubrication system are electrically connected with the control cabinet respectively, the driving system is used for driving the to-be-tested main bearing to rotate, the loading system comprises an axial loading device, a radial loading device and an overturning moment loading system, the lubrication system comprises an oil injection pump and an oil injection pipe, a temperature sensor is installed in an axial groove of the main bearing fixing seat, and a lubricating oil nozzle is installed on a cylinder for sealing a rear cover plate. The system disclosed by the invention can study the distribution characteristics of the temperature field of the main bearing under single-acting load or multiple-load coupling, and can alsostudy the distribution characteristics of the temperature field of the main bearing under different rotating speeds, good lubrication, lubrication failure and non-lubrication states.